Mold-coating.



UNITED STATES PATENT oFnioE;

CHARLES H. HASLETT 'nND ALBERT A. MENTZER, OEPITTSBURGH, PENNSYL ANIA.

' 'MoLn-ooA'riNe.

No Drawing.

To all whom it may concern: g

Be it known that we, CHARLES H. HASLETT and ALBERT A. Mnxrznu, citizens of the United States of America, residing at Pitts burgh, in the county of Allegheny a'nd'State that when the metal is poured it will not sweat or run through the walls and render the casting unfit for use. Many experi ments have been made and processes developed for the purpose of eliminating these disadvantages, but so faras we are awarenone of them have proven successful, so that there is such uncertainty as to the results which will accrue uponthe pouring of the;

metal as to render the cost of making :cast-' ings from such metals excessive and timeconsuming, by reason of, the fact that in a majority of cases more than a single 'attempt must be made-- before obtaininga casting sufliciently perfectto enable the comlete action, and even then the casting must e operated upon by workmen for a' considerable length of time in order to ,place' it in within its desired limits; in casting, the a condition for machine work. As an example, the molds made for. cast-v ing gear wheels require thevpresenceof a large number of reinforcements (some molds. requiring at least four hundred pounds of IlfillSOl other form of reinforcing metal) in order toenable the walls to withstand the v heat and pressure, and even then there is no certainty that the metal will be confined metal unites with the steel and requires a trimming -of the. casting toremove this metal. When cores-are employed,.vand especially cores of comparatively small di- 7 ameter, the molten metal sweats through the core and practically destroys the cavity or 1 opening which is to be provided by the co re and wh, e the core contains a metallic re-, inforceiii ent, this reinforcement unites with Specification of Letters Patent.

the metal and renders'it 'exceedingly-difiicult Patented Mar. a6, 1912'.

Application filed July 10, 1911. Serial No. 637,784.

tocomplete such cavity or opening. -The coating or wash which forms the subject- 'matter of thepresent invention is designed to eliminate these difiiculties,.m olds treated therewith requiring no'metallic reinforcemerit and, so far as has been demonstrated .byrepeated experiments, preventing sweating. and a running of the molten metal beyond the confines of the mold.

lVe; have treated molds for castings of various sizes and shapes, including gear wheels where acastingpressure of from A forty to ninety pounds has beenemployed;

in'preparing the mold for such casting we have employed no metallic reinforcement to the walls of the mold cavity. and the initial casting proved perfect. expeiiienc'e witheach mold which has been treated by us): \Ve have also prepared (This has been our cores for use in molds, coating them with v the coating or wash, and the face ofthe core has, in each instance, withstood thepressure and heat so as to prevent sweating. eventhough the-core was of small diameter and prepared without the use ofreinforceinents.

v The coating orhwash employed byus composed of alum, preferably in powdered form, and water, thoroughly inixed; the

alum being'dissolved in the water in suitable manner as by the application of heat. I :Th'e proportions of the elements may vary according to the character of the mold to be treated, one part of the alum to] from sixty to one-hundred parts of water being employed. This form of coating or wash is employed when the sand contains a substance which acts to provide a body to the sand, )a preferred form of such' substance being the preparation known as glutrin used for this purpose. \Vhen the sand does not contain such body, we add glut 'in to the wash in the proportion of about six parts of glutrin to one part of-alum, thereby adding the body to the sand'with the composition. When the latter form ofthe compo- "sition isprovided, the component parts are I .placed in a receptacle, thoroughly. stirred,

and then subjected to the action of heat until the solution boils; after boiling for aperiod of time, preferably about an hour, it is allowed to cool and is then ready for use.

In preparing a moldfor the pouring of the 'molten metal, the facing sand is provided. to, form the face walls of the cavity or :of the core, depending. upon the mold to be formed, as is usual. The facing sand preferably is provided with the substance to form the body, such as glutrin, by being worked therein as is usual. Aftenthe mold has been completed in the usual manner, and

the pattern removed, the exposed face or faces of the cavity or surface of a core are coated with the alum and water solution by any suitable means such as a swab, after which the mold is baked or skin-dried in a suitable oven for ashort period. This baking operation causes the exposed face or facesof the mold cavity or core to become hardened, the depth to which the hardening extends depending upon the length of time 15' the mold is baked, it not being essential, in order to provide the desired results, that the entire mold be dried orbaked,we having obtained the desired result when the main portion of the mold remained damp or wet. This hardened surface does not destroy the porosity of the mold, but acts to prevent sweating or 'a running of the molten metal" through. the Wall during the pouring open the;sand particles and the metal, thereby freeing the casting from the sand particles. 'One feature in connection with the use of the composition in either of its forms indicated is the fact that while the faceof the mold becomes exceedingly hard and difiicult to destroy or affect when thG'IIlOlCi has been .baked, the'application of either the solution or face and leaves the sand in condition for being again used. Our own experience has demonstrated the fact that the oftener the sand treated in this manner is employed in the making of castings, the more perfect will be the results obtained.

It is to be understood that by the term face walls we include the walls of a mold cavity or the surface of a core. WVe also desire it to be understood that the invention contemplates a composition with or without the glutrin, the latter being a preferred preparation for providing the body to the sand of the mold, it being understood that. the particular form of the composition employeddepends upon whether"the sand contains such body before the making of the mold or if it is absent therefrom.

Having thus described our .invention, what we claim as new is 1. A wash fortreating the walls of a sand moldfor making metal castings, composed of alum and water in solution form.

2. A wash for treating the walls of a sand mold for making metal castings, composed of alum and water in solution form, and a substance to provide a body to the sand of the mold.

3. A wash for treating the face walls of a 

